This invention is directed to a method for recycling contaminated plastic, and to improved plastic formulations provided thereby.
In industries using plastic material for particular products the creation of scrap product, is inevitable. In the case of product incorporating components such as laminations, adhesives coatings such as polyester film, Mylan in plain or metallized form, reclamation of such scrap has previously required the physical removal of the contaminating components, before remelting the scrap.
Failure to remove the contaminants results upon melt down of the material in a black coloured product not normally suitable for use except in block form.
It has been found that such contaminated plastic can be recycled to an effective product having unexpectedly advantageous characteristics without the need of mechanical or other manner of removal of the contaminating elements.
The method involves the step of chilling the contaminated plastic material to an embrittlement temperature, and pulverising the chilled material to a finely divided consistency. It has been found that chilling of the plastic to a temperature in the range of -150.degree. F. to -200.degree. F. followed by pulverisation to a powder results in a material suited for re-use, and possessing the following unexpected characteristics;
(a) the powdered material may be pelletised, or PA1 (b) heated and extruded through a desired die, or PA1 (c) the plastic is susceptible to influence by colour; PA1 (d) the resulting extruded material is a closed-cell spontaneously foamed material capable of providing a good surface finish and having a density 20 to 40% less than the untreated contaminated starter material, while possessing enhanced softness, dimensional stability, and improved resistance to delamination (i.e. improved adhesiveness). PA1 (e) the process has unexpected benefit that the treated material retains no residual memory.
The process generally is practiced by carrying out an initial grinding step to reduce the material to a more readily processed product.